The invention relates to a chart and a method for evaluating skin color, such as yellowness in a mammalian subject. The invention further relates to the use of the chart for assessment of skin color changes, for example, in clinical grading and consumer self-assessment of skin improvement or skin color change.
The ultimate goal of a cosmetic composition for skin lightening or anti-aging, as well as that of any other cosmetic product or method, is a satisfied consumer. When using cosmetic skin lightening or anti-aging products, a consumer seeks some degree of visible skin lighting or reduction of age-related skin characteristics, respectively. While many cosmetic products advertise skin lightening or anti-aging benefits, consumers usually cannot easily discern whether the claimed benefit is actually delivered, or a quantitative extent to which it is delivered.
Color instruments are known for color measurements in L*-a*-b* color space according to Commission Internationale de l'Eclairage (CIE) standard. Currently, however, communication with respect to skin yellowness improvement is neither clear nor convenient. Although color instruments are very useful and provide objective data, verbal description is subjective and not accurate. In fact, the yellowness parameter in CIE-LAB color space is rather abstract as it involves a numeric scale range from −50 to 50, representing blue (b*=−50) to yellow (b*=50). In other words, visual assessment is also important in evaluating skin lightening efficacy. After all, it is consumers (human eyes) that evaluate the efficacy or other effect of skin lightening or anti-aging products. Therefore, for visual assessment of color, it is desirable to have a tool as an objective scale for grading.
Phillips et al., “Efficacy of 0.1% Tazarotene Cream for the Treatment of Photodamage,” Arch Dermatol, vol 138, p 1486-1493 (November 2002) describes a 5 point scale (0: none −4: severe), noticeable to patients and investigators, for measuring hyper-pigmentation and other conditions. Japan Color Research Institute launched a skin tone color product that can be seen at http://plaza16.mbn.or.ip/˜JCRI/seihin/skintone.htm. However, skin texture is not shown in this product, which appears to have simply been based on paints.
A scale for evaluating wrinkles is disclosed in Tsukahara et al., “A Photographic Scale for the Assessment of Human Facial Wrinkles,” J. Cosmet. Sci. 51:127-139 (March/April 2000). However, no objective scale for evaluating facial color is reported.
A self-assessment proof strip for evaluating skin lightening progress is discussed in WO 2009/059856. However, the strip for evaluating skin includes images from consumer averaged photographic captured shade batches, which are further “fine-tuned” to match the local populations. The reference does not mention evaluating a specific color of the skin, such yellowness.
Accordingly, there is a need for a tool for the objective visual measurement of attributes of human skin color, especially, for example, yellowness properties of the skin.